Immunosuppressive related indolent cytotoxic T-cell lymphoproliferative disease of the gastro-intestinal tract in a patient with Crohn's colitis Edison N1,2, Eitan Y2, Belhanes-Peled H2, Gutman Y2, Elmalah I2 and Trougouboff P1,2 Hematopathology unit1, Tissue Diagnosis and Cancer research institute2, Emek Medical Center, Afula, Israel TCRB TCRG Abstract -12m -36m 3m 12m 200 300 4500 3000 1500 6500 100 150 200 We describe the unusual case of a 27 year old patient treated with TNF-α inhibitor (Adalimumab) for resistant Crohn's disease, who developed a primary intestinal CD8+ cytotoxic indolent T-cell lymphoproliferative disease (iTCLPD) after the initiation of the immunosuppressive treatment. At our knowledge it is the first time that the close correlation between immunosuppression and the development of a clonal T-cell population is observed. Since this iTCLPD mimics T-cell lymphoma of the gastrointestinal tract, an aggressive disease associated with a dire prognosis, such cases of iTCLPD should be recognized to avoid a misdiagnosis and inadequate aggressive treatment for the patients. Background TNF-α inhibitors are more and more used to treat Crohn's disease irresponsive to conventional treatment. Unfortunately lymphomas, among them Hepatosplenic T-cell lymphoma (HSTCL), are a increasingly recognized complication of immunosuppressive treatments for autoimmune and inflammatory diseases. iTCLPD of the gastrointestinal tract are a recently described entity that mimics T-cell lymphoma and could lead to misdiagnosis and inadequate therapy (Perry AM et al, Blood 2013; Leventaki V et al, Human Pathology 2014). Fig. 3: Gene scan of PCR study for T-cell clonality (BIOMED-2) revealed a monoclonal population positive for TCRB and TCRG re-arrangements, appearing shortly after the initiation of the anti-TNF-α inhibitor treatment, that progressively regressed after the withdrawal of the immunosuppressive therapy. CD4 CD8 3m 12m 9m Results CD3 CD8 CD4 TIA1 CD20 HE Fig. 4: The CD8-positive T-cell infiltrate in the lamina propria regressed after cessation of the TNF-α inhibitor (Original magnification x100) TNF-α inhibitor treatment was discontinued and a "wait and see" follow up was adopted, without any cytotoxic treatment. The subsequent endoscopic biopsies at three, six months and 1 year after the original diagnosis showed a gradual restoration of the CD4 and CD20 population and a regression of the CD8 positive T-cell infiltrates. Discussion This case raises several questions. The CD4/CD8 ratio of the associated T-lymphocytes in all the patients with Crohn's disease we studied for control was within normal limits (data not shown). In our case the patient presented an inversed CD4/CD8 ratio in all the biopsies taken since 2007, without evidence of clonality. The addition of a TNF-α inhibitor resulted in the development of a TCR-αβ clonality, that significantly regressed after its withdrawal. The number of Crohn’s disease patients presenting an abnormal CD4/CD8 ratio is still unknown. Furthermore the mechanism underlying the apparition of T- clonality during inhibition of TNF-α is yet to be elucidated. In the case we studied, a causal relation between the atypical CD8 T-cell population and the development of this iTCLPD could be considered. Fig. 1: Colonic endoscopic biopsy at the time of original diagnosis shows dense CD8+ cytotoxic T-cell lymphoid infiltrate in the lamina propria, without crypt destruction, or significant intra-epithelial lymphocytosis. Original magnification x400. Biopsies of the colon showed a characteristic picture of focal active Inflammatory Bowel Disease (IBD). These foci were associated with a dense non-destructive infiltrate of small lymphocytes, stained for CD2, CD3, CD5, CD7, CD8, with only few CD4 positive T-cells and small aggregates of CD20 positive B-cells. The CD8 positive T-cells were TIA-1 positive and negative for Granzyme-B, CD56, CD57, CD30 (not shown) and an ISH study for EBV (EBER) was negative. CD4 CD8 -6y -5y -3y -1y Conclusions With the increased use of immunosuppressive drugs for autoimmune and chronic inflammatory diseases such cases of iTCLPD should be recognized to avoid misdiagnosis and inadequate aggressive treatment for the patients. Our results show a clear correlation between the behavior of the CD8 positive T-cell monoclonal population and the TNF-α inhibitor therapy. Furthermore, before initiation of an immunosuppressive therapy it could be relevant to check the T-cell population of the patient and closely follow its evolution. Fig. 2: Colonic endoscopic biopsies up to 6 years prior the TCLPD diagnosis show dense CD8 cytotoxic T-cell lymphoid infiltrates and a prominently decreased CD4 positive population. Original magnification x100. The previous endoscopic biopsies at one, three, five and six years before the original diagnosis showed dense non-destructive infiltrates of small CD8 positive lymphocytes, with an already inversed CD4/CD8 ratio (1/4 or less). There was no significant intra-epithelial T-cell infiltration. No evidence of clonality for TCR rearrangement (BIOMED-2) was found at these points (see Fig. 3).